1. Field of the Invention
The present invention is related to an anti-theft device for use in securing a vehicle, and more particularly to an anti-theft device which selectively enables and disables vital electrical components powered by a vehicle's electrical system.
2. Description of the Prior Art
Various anti-theft devices have been developed to secure automobiles and other vehicles. Known prior art anti-theft devices typically include a central control unit and a plurality of disabling circuits. The central control unit is powered by the vehicle's battery and is typically attached to the interior of the vehicle. The disabling circuits are directly wired to the central control unit and are coupled with various electrical components of the vehicle for controlling the delivery of power to these components. The disabling circuits normally disable the operation of the controlled vehicle components. Once a predetermined code is entered into the central control unit, an enabling signal is transmitted to the disabling circuits to switch power to the controlled vehicle components. The enabling signal is transmitted over the wires connecting the disabling circuits to the central control unit.
Prior art anti-theft devices suffer from several limitations that limit their utility. For example, since the central control units of prior art anti-theft devices are directly wired to the vehicle battery, they are easy to locate and disable. A thief can easily trace the wiring leading from the vehicle battery or fuse box back to the central control unit and disable the anti-theft device. Similarly, since the central control units are directly wired to the disabling circuits, the disabling circuits can also be easily located and disabled by tracing the wires leading from the central control units. Thus, a thief locates the central control unit, he or she can follow the direct wiring to the disabling circuits and disconnect them from the vehicle. This allows a thief to quickly and easily circumvent the anti-theft device.
Another limitation of prior art anti-theft devices is that they are difficult and costly to install due to the direct wiring.
To avoid the problems associated with anti-theft devices using direct wiring and central control units, wireless anti-theft devices have been developed. Typical wireless anti-theft devices include a plurality of disabling circuits connected to vital components of the vehicle which are controlled by a wireless transmitter. The transmitter transmits either an activation or deactivation signal to the disabling circuits to either arm or disarm the disabling circuits. Although prior art wireless anti-theft devices solve some of the problems associated with direct wired anti-theft devices, they also suffer from several limitations. For example, although these wireless anti-theft devices are not controlled by central control units, their disabling circuits are directly wired to a central power unit for receiving power. Accordingly, these wireless disabling circuits are also easy to locate and disable by tracing the wire leading from the central power unit.
Another limitation of prior art wireless systems is that their disabling circuits are activated by an activation signal which is a widely broadcast standard FM signal or infrared signal. These widely broadcast signals propagate over long distances and can be easily intercepted and copied with a conventional receiver and recorder. The copied signal can then be rebroadcast to disable the disabling circuits of the wireless anti-theft device. Thus, prior art wireless anti-theft devices are also easy to circumvent.
Accordingly, there is a need for an improved vehicle anti-theft device that overcomes the limitations of prior art anti-theft devices. More particularly, there is a need for a vehicle anti-theft device that is easy to install and difficult to circumvent.